What is the statistical risk of an allergic reaction to contrast media (Contrast-Induced Allergic Reaction)?

From the Guidelines

The statistical risk of an allergic reaction to contrast media is approximately 1%, with severe reactions occurring in about 0.04% of cases. This risk is based on the most recent and highest quality study available, which reported that the incidence of anaphylactoid reactions to contrast media is 1%, and the incidence of severe reactions may be as low as 0.04% 1. The following key points are relevant to understanding the risk of contrast-induced allergic reactions:

• The recurrence rate without prophylaxis in patients with a history of prior anaphylactoid reaction is in the range of 16% to 44% 1.
• Adequate pretreatment of patients with prior anaphylactoid reactions reduces the recurrence rate to close to zero 1.
• A regimen of 50 mg of prednisone administered 13 hours, 7 hours, and 1 hour before the procedure (as well as 50 mg of diphenhydramine 1 hour before the procedure) has been shown to reduce the risk of recurrent anaphylactoid reaction 1. It is essential to note that patients with a history of seafood or shellfish allergies are not at increased risk for an anaphylactoid reaction from exposure to contrast media, as iodine does not mediate seafood, shellfish, or contrast media reactions 1. In clinical practice, pre-medication protocols using corticosteroids and antihistamines can be effective in reducing the risk of contrast-induced allergic reactions in high-risk patients 1.

From the FDA Drug Label

Reported incidences of death range from 6.6 per 1 million (0.00066 percent) to 1 in 10,000 (0. 01 percent). The statistical risk of an allergic reaction to contrast media is reported to be between 0.00066% and 0.01% 2.

• The risk of death due to anaphylactoid shock is estimated to be between 1 in 10,000 and 6.6 per 1 million.
• Patients with a history of allergy are twice as likely to experience an adverse reaction, while those with a history of previous reactions to contrast media are three times more susceptible 2, 2.

From the Research

Statistical Risk of Allergic Reaction to Contrast Media

The statistical risk of an allergic reaction to contrast media, also known as Contrast-Induced Allergic Reaction, is estimated to be:

• 0.05%-0.1% of patients undergoing radiologic studies with iodinated contrast media (ICM) 3
• 0.04 % - 0.22 % of patients for radiocontrast agents (RCA) allergy 4
• 0.66% overall adverse reaction incidence, with 0.05% severe adverse reactions 5
• 0.01% to 2% for gadolinium-based contrast agents (GBCAs) immediate reactions 6

Risk Factors for Allergic Reactions

The risk factors for immediate reactions include:

• Poorly controlled bronchial asthma
• Concomitant medication (e.g., angiotensin-converting enzyme inhibitors, ß-blockers, and proton-pump inhibitors)
• Rapid administration of the ICM
• Mastocytosis
• Autoimmune diseases
• Viral infections 3
• Prior history of RCA allergy, with an increased risk of 16 % to 35 % 4
• Age < 70 years and absence of hypertension may be risk factors for ICM-related AR in patients with non-ICM allergies history 5

Symptoms of Allergic Reactions

The most common symptoms of immediate reactions are:

• Erythema and urticaria with or without angioedema, which appear in more than 70% of patients 3
• Maculopapular rash is the most common skin feature of nonimmediate reactions (30%-90%) 3
• Urticarial, itching, dyspnea, and chest tightness, angioedema during coronary artery stenting 4